The invention relates to an apparatus for manufacturing a foil web of a thermoplastic with locally secured fittings for use as tarpaulins or similar articles, comprising an extruder head with an entirely or mainly downwards directed ejection orifice and two counterrotating rollers or similar members arranged below the ejection orifice, at least one of said rollers or members being cooled, said rollers or members forming between them a nip for calibrating the extruded foil, and a feeding device with an entirely or mainly vertical supply magazine for accomodating a stack of fittings, a discharge duct extending from the bottom of the supply magazine in a direction towards the roller nip and a guiding device for guiding the lowermost fitting in the magazine into the discharge duct.
An apparatus of this kind, which is used for example for the fastening of eyelets in a plastic foil web, which is subsequently to be cut in suitable lengths for production e.g. of tarpaulins for covering purposes in construction works is known from DK-published patent application No. 130 239.
In this prior art apparatus the guiding device formed as a reciprocating slide is driven by a hydraulic or pneumatical working cylinder and the discharged duct of the feeding device is arranged and designed in such a way that the supplied fittings are guided from the mouth of the duct towards the roller nip by the cooled roller.
Thereby, it is only possible to obtain a relatively inaccurate positioning of the fitting in the foil web, since the velocity with which the fittings are supplied from the mouth of the discharged duct is mainly determined by the stroke velocity of the slide.
The ejection of fittings may thereby in an unpredictable way take place at such a velocity, that the fittings strike holes in the soft foil web.
When a number of feeding devices arranged on a line in the axial direction of the rollers are used for fastening fittings along a corresponding line in the foil web in one operation, local differences in the surface character of the cooled roller has moreover led to a releatively inaccurate supply of the fittings of the roller nip.
Whereas these disadvantages have to a certain extent been acceptable in case of foil tarpaulins for singular use, they are not acceptable, when a greater number of tarpaulins are used for covering in construction works and arranged with overlapping edges since the said inaccuracies entail that the eyelets along the overlapping edges cannot be positioned opposite each other.